The line between comedy and drama is usually sharply defined. Not so in “Calvary,” which blurs the line to such an extreme that it’s genuinely disarming. The subject is the Catholic Church abuse scandal. In the opening scene, a priest, Father James (Brendan Gleeson), is informed by a mystery parishioner in his small, seaside Irish village that in a week he’s going to kill him. The man was abused as a kid, and he wants to strike back by killing a good, innocent priest, in part because the man who abused him is long dead.

But this scene, like every single one that follows, doesn’t stick to one tone. It bobs and weaves, going from serious to funny on a dime. The man is troubled, and there’s no easy remedy for his trauma; at the same time there’s something absurdist about his demands, and something strangely amusing about the calm way Father James takes the news. It carries through the rest of the film, which follows Father James — said to be “just a little too sharp for this parish” — as he doesn’t exactly try to escape or put his affairs in order, but rather bums around the village, looking for a final sense of meaning or closure.

The search for levity proves cumbersome, as he’s surrounded by grotesques — from Dylan Moran’s bored, lonely Richie to Chris O’Dowd’s casually cuckolded butcher to Aiden Gillen’s argumentative, atheistic doctor (who says he has a thing for widows). Gleeson is not just the straight man but the grumpy straight man, who brings to each visit weary disdain and quips as good as he’s given.

Dylan Moran (left) is one of the many grotesques in a seaside Irish village in "Calvary."Credit: Fox Searchlight

Writer-director John Michael McDonagh is working in a different register than in his previous film, the very funny “The Guard,” but that doesn’t mean he cuts down on killer one-liners. The dialogue is punchy and worthy of jotting down, but it can also be self-aware (“How’s that for a third act twist?” someone says during the third act twist) or turn on itself. One seemingly aphoristic utterance is said by Father James to be “one of those lines that sounds witty but makes no sense.”

That there are gobs of jokes in a movie ostensibly about unimaginable pain caused by an institution that was trying to cover it up may seem questionable, and sometimes one could accuse the film of not taking itself as seriously as it should. (A sequence that seems to mock the end of “American Beauty” probably belongs in a goofier movie.)

But the humor doesn’t necessarily mean the film is dodging the issue. It helps complicates a film that doesn’t want easy answers, that knows there’s no treatment, perhaps at all, for people molested in childhood. The way “Calvary” bobs between serious and comedic — while always being prickly — mirrors how the film as a whole refuses to settle for anything. It embraces complexity and chaos rather than tries to tame them. It attacks the Catholic Church without taking it down completely. And it deals with trauma while making jokes about a certain unprintable, Google-able sex act.